Safety authorities say flying rideshare taxis are feasible and could be in Australia within five years.

The he Civil Aviation Safety Authority (CASA) has been processing proposals for low-altitude air taxi services that would fly people between locations such as an airport and the central business district of a large city.

“There are companies, and I'm talking about big multinational companies, investing big dollars,” CASA spokesperson Peter Gibson said.

“We are talking about hundreds of millions, if not billions.”

It comes after Uber announced it was considering Melbourne or Sydney among possible cities to test its Elevate project, which would use an electric aircraft able to take people between specific points within a city.

Plans are in place to offer the service in Dallas and Los Angeles in the United States.

Reports say Google's parent company, Alphabet, is also preparing to trial drones for home deliveries in Canberra.

CASA has been talking with Uber and other companies about the regulatory issues in the use of air taxis, but much of the regulatory framework to allow it is already in place.

“It's a bit like you can just go and charter a helicopter at Brisbane to go to the Sunshine Coast,” Mr Gibson said.

“That's all they're doing, but they're doing it in an electric aircraft controlled by a traffic management system and they're doing it a price point cheaper than you could hire a helicopter.”

Uber says it wants to use human pilots at first to monitor the aircraft's progress and intercede if something goes wrong.

Experts say developing a traffic management system that would allow aircraft to fly autonomously would be easier than creating one for driverless ground vehicles.